<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        ul{
            width: 220px;
            height: 220px;
            position: relative;
            margin: 0 auto;
        }
        li{
            list-style: none;
            border-radius: 50%;
            position: absolute;
            top: 0;
            bottom: 0;
            left: 0;
            right: 0;
            margin: auto;
        }
        li:nth-child(1){
            width: 200px;
            height: 200px;
            background-color: black;
        }
        li:nth-child(2){
            width: 180px;
            height: 180px;
            background-color: #0000ff;

        }
        li:nth-child(3){
            width: 160px;
            height: 160px;
            background-color: #ffff00;

        }
        li:nth-child(4){
            width: 140px;
            height: 140px;
            background-color: #008000;
        }
        li:nth-child(5){
            width: 120px;
            height: 120px;
            background-color: #ff0000;
        }
        li:nth-child(6){
            width: 100px;
            height: 100px;
            background-color: #ffa500;
        }
        li:nth-child(7){
            width: 80px;
            height: 80px;
            background-color: #0000ff;
        }
        li:nth-child(8){
            width: 60px;
            height: 60px;
            background-color: #ffff00;
        }
        li:nth-child(9){
            width: 40px;
            height: 40px;
            background-color: #ff0000;
        }
        li:nth-child(10){
            width: 20px;
            height: 20px;
            background-color: black;
        }
    </style>
</head>
<body>
<ul>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
    <li></li>
</ul>
</body>
</html>
